a. Field of the Invention
This invention relates to 5-[1H-(5-membered-N-aromatic-heteryl-1-yl)]-1,6-naphthyridin-2(1H)-ones, their cardiotonic use, their preparation and intermediates.
b. Information Disclosure Statement
Lesher and Singh in U.S. Pat. No. 4,415,580, issued Nov. 15, 1983, show as cardiotonic agents 5-(loweralkyl)-1,6-naphthyridin-2(1H)-ones (I) and their preparation by reacting a 5-(lower-alkanoyl)-6-methyl-2(1H)-pyridinone with di-(lower-alkyl)formamide di-(lower-alkyl) acetal to produce 5-(lower-alkanoyl)-6-[2-(di-lower-alkylamino)ethenyl]-2(1H)-pyridinone (II) and reacting II with formamidine or ammonia or salt thereof to produce I.
Czuba et al., Pol. J. Chem. 52, 2369-76 (1978), show as intermediates 4-bromo-1,6-naphthyridin-2(1H)-one and 4-hydrazino-1,6-naphthyridin-2(1H)-one. This reference also shows the preparation of 4-bromo-1,6-naphthyridin-2(1H)-one by heating 2,4-dibromo-1,6-naphthyridine with 20% hydrobromic acid and the preparation of 4-hydrazino-1,6-naphthyridin-2(1H)-one by heating 4-bromo-1,6-naphthyridin-2(1H)-one with hydrazine.
Paudler et al., J. Heterocyclic Chem. 2 (4), 393-8 (1965), show the synthesis and NMR spectra of various 4-substituted-1,6-naphthyridines, for example, the reaction of 4-hydroxy-1,6-naphthyridine with POBr.sub.3 or POCl.sub.3 to obtain 4-bromo-1,6-naphthyridine or 4-chloro-1,6-naphthyridine, respectively. Also shown is the reaction of 4-bromo-1,6-naphthyridine with dimethylamine to produce 4-dimethylamino-1,6-naphthyridine and the reaction 4-chloro-1,6-naphthyridine with piperidine or hydrazine to produce 4-(1-piperidinyl)-1,6-naphthyridine or 4-hydrazino-1,6-naphthyridine, respectively.
Rooney et al. U.S. Pat. No. 3,993,656, issued Nov. 23, 1976, shows various substituted-1,8-naphthyridin-2(1H)-ones having bronchodilating and hypotensive properties, including 6-(2-imidazolyl)-1,8-naphthyridin-2(1H)-one and its preparation from 2-amino-6-(2-imidazolyl)-1,8-naphthyridine.